In a factory automation (FA) field, a technique for controlling various processes using image processing is frequently used for the purpose of labor-saving. As an application example of such an image processing technique, there has been know a process in which while a conveyer such as a belt conveyer conveys workpieces, a moving machine (hereinafter referred to as an “industrial robot” or simply referred to as a “robot”) tracks and grasps the conveyed workpieces. The work process is called conveyer tracking or the like.
In the conveyer tracking technique, an imaging device images the workpiece on the conveyer, and an image processing apparatus performs measurement processing such as pattern matching and binarization processing to an image obtained by the imaging device, thereby identifying an existence position (a coordinate) of each workpiece. The robot tracks and grasps each workpiece based on the identified position (the coordinate) of each workpiece.
For example, Patent Document 1 (Japanese Unexamined Patent Publication No. 09-072717) discloses a configuration that is applied to tracking processing or the like of the robot by performing image acquisition/image processing with a simple system in which a visual sensor is used.
Although not used in the conveyer tracking, for example, Patent Document 2 (Japanese Unexamined Patent Publication No. 2005-293567), Patent Document 3 (Japanese Unexamined Patent Publication No. 2005-063176), and Patent Document 4 (International Patent Publication WO2006/075354) can be cited as prior art documents related to the visual sensor.
Patent Document 2 discloses a measurement device that can output a measured value of a measurement target to an external control device together with information on the time when the measured value is obtained.
Patent Document 3 discloses an object recognition device that recognizes a state of the workpiece by performing the image processing to an imaging result of an object, such as the workpiece on the conveyer, which moves relative to imaging part. Particularly, Patent Document 3 discloses the object recognition device that can accurately obtain a positional relationship between the imaging part and the workpiece at imaging timing and an image processing result.
Patent Document 4 discloses a configuration in which, although not used in the conveyer tracking, in the case where the workpiece as a semiconductor chip is placed on an XY-table without performing positioning, the workpiece is imaged with a camera to position the workpiece to a previously assigned position.